Prior art workers have devised many types and sizes of open-top, bottom-discharging railroad cars, generically termed hopper cars. Such cars have been designed for many types of lading, including (but not limted to) coal, aggregate, wood chips and the like.
Such cars, when loaded, are brought to unloading stations where their bottom hopper doors are opened. The lading is discharged through appropriate openings between the railroad rails to bins, conveyors, or the like located beneath the railroad rails. The hopper doors may extend transversely of the longitudinal center sill of the car, or they may extend parallel to the center sill. The hopper doors may be opened manually or through the agency of mechanical door opening devices, depending upon the design of the car.
In many instances, the lading is not easily discharged. Normal, over-the-road shifting and vibration of the car tends to compact the lading therein. Frequently, the lading gets wet and/or frozen. As a result, it is not unusual to provide one or more mechanical car shakers to operate on the hopper car during the lading discharge operation, to assist and speed up the discharge opera- tion.
Many types of car shakers have been developed. Shakers most frequently used with open-top, bottom-discharge hopper cars comprise frame-like members which extend transversely of the hopper car, spanning the hopper car and engaging the upper horizontal surfaces of the top chords of the hopper car sides. The shaker has a pair of downwardly depending stop members located near each top chord and capable of abutting the in-board surface of the adjacent car side top chord to prevent the shaker from "walking" off the car side top chords in a direction transverse the hopper car. The shaker generally employs a weighted eccentric which is rotated by an appropriate prime mover. The rotating eccentric imparts violent shaking to the shaker, which in turn is imparted to the car by virtue of the shaker's contact with the top chords of the car sides. In some unloading facilities, more than one shaker is applied to a given hopper car. In some instances, one or more shakers are indexed along the hopper car. In other instances, the hopper car, itself, is indexed with respect to one or more shakers.
The forces imparted to the hopper car by a shaker are primarily vertically oriented forces. As will be explained hereinafter, means are provided to confine these forces as near to the plane of the side sheets as is possible. Nevertheless, a shaker imparts to the car sides and their top chords vertical forces far in excess of those normally experienced in over-the-road travel and the like. Therefore, it is of utmost importance that the attachment of the top chords to their respective sides of the hopper car be sufficiently strong and rigid to prevent failure of this attachment and consequent damage to the related parts due to the action of one or more car shakers. The present invention is applicable to any hopper car of the type wherein the top chords are joined to their respective hopper car sides with fastening means. The fastening means can be of any form. As a non-limiting example, the fastening means can comprise rivets, two-piece rivets, bolts or the like. While the teachings of the present invention are clearly applicable to hopper cars of all steel construction, in recent years considerable interest has been directed to aluminum-steel hopper cars wherein the car underframe is made of steel and substantially the entire body supported thereby is made of aluminum. Such cars provide a considerable weight savings. The teachings of the present invention are particularly applicable to such cars.